ps\2 keyboard with PS3

i have read in some threads and they say that to use a ps\2 keyboard on a PS3 all you need is a ps\2 to usb converter,but with mine the lights on it go on, then off again, and the keyboard doesn't work. Can anyone help???

but i tried two, and my bro got my pc keyboard working again, but i don't know how, and he went back to university today so i am afraid to take it out and try it in my PS3 again incase i can't get it to work again.